Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades, as shown in FIG. 1, are formed from a root portion at one end and an elongated portion forming a blade that extends outwardly from a platform coupled to the root portion at an opposite end of the turbine blade. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. The inner aspects of most turbine blades, as shown in FIG. 2, typically contain an intricate maze of cooling channels forming a cooling system. The cooling channels in the blades receive air from the compressor of the turbine engine and pass the air through the blade. The cooling channels often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature. However, centrifugal forces and air flow at boundary layers often prevent some areas of the turbine blade from being adequately cooled, which results in the formation of localized hot spots. Localized hot spots, depending on their location, can reduce the useful life of a turbine blade and can damage a turbine blade to an extent necessitating replacement of the blade.
Many conventional turbine blades have relatively thick outer walls, as shown in FIG. 3. It is understood in turbine blade design that the cooling efficiency of a turbine blade may be improved by reducing the cooling channel wall thickness. However, a reduction in cooling channel wall thickness causes an increase in the cross-sectional area of the cooling channel, which reduces the internal Mach number and the velocity of cooling fluids through the cooling system in the blade. The reduction in cooling fluid flow velocity causes the internal heat transfer coefficient to be reduced as well. Therefore, simply reducing the external wall thickness does not increase the efficiency of a cooling system. Thus, a need exists for a cooling system for a turbine blade that incorporates the advantages of a thin wall turbine blade while overcoming the reduced internal heat transfer coefficient and reduced internal Mach number associated with conventional cooling systems of thin wall cooling systems.